ADAMTSL4-associated isolated ectopia lentis: Further patients, novel mutations and a detailed phenotype description.

ADAMTSL4 mutations seem to be the most common cause of isolated ectoplia lentis (EL) and thus are important concerning the differential diagnosis of connective tissue syndromes with EL as main feature. In this study, we describe an additional cohort of patients with apparently isolated EL. All underwent a detailed clinical exam with cardiac evaluation combined with ADAMTSL4 mutation analysis. Mutations were identified in 12/15 patients with EL. Besides the European founder mutation p. (Gln256Profs*38) we identified five further mutations not yet described in the literature: p. (Leu249Tyrfs*21), p. (Ala388Glyfs*8), p. (Arg746His), p. (Gly592Ser), and p. (Arg865His). Clinical evaluation showed common additional ocular features such as high myopia, but no major systemic findings. In particular: no dilatation of the aortic root was reported on. This report increases the total number of patients with ADAMTSL4 mutations reported on today and reviews in detail the clinical findings in all patients reported on to date demonstrate, that these patients have a mainly ocular phenotype. There are no consistent systemic findings. The differentiation between syndromic and isolated EL is crucial for the further surveillance, treatment, and counseling of these patients, especially in young children.

Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: urinary organic acid profiles and expanded spectrum of mutations.

Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase (HMCS2) deficiency results in episodes of hypoglycemia and increases in fatty acid metabolites. Metabolite abnormalities described to date in HMCS2 deficiency are nonspecific and overlap with other inborn errors of metabolism, making the biochemical diagnosis of HMCS2 deficiency difficult. Urinary organic acid profiles from periods of metabolic decompensation were studied in detail in HMCS2-deficient patients from four families. An additional six unrelated patients were identified from clinical presentation and/or qualitative identification of abnormal organic acids. The diagnosis was confirmed by sequencing and deletion/duplication analysis of the HMGCS2 gene. Seven related novel organic acids were identified in urine profiles. Five of them (3,5-dihydroxyhexanoic 1,5 lactone; trans-5-hydroxyhex-2-enoate; 4-hydroxy-6-methyl-2-pyrone; 5-hydroxy-3-ketohexanoate; 3,5-dihydroxyhexanoate) were identified by comparison with synthesized or commercial authentic compounds. We provisionally identified trans-3-hydroxyhex-4-enoate and 3-hydroxy-5-ketohexanoate by their mass spectral characteristics. These metabolites were found in samples taken during periods of decompensation and normalized when patients recovered. When cutoffs of adipic >200 and 4-hydroxy-6-methyl-2-pyrone >20 µmol/mmol creatinine were applied, all eight samples taken from five HMCS2-deficient patients during episodes of decompensation were flagged with a positive predictive value of 80% (95% confidence interval 35-100%). Some ketotic patients had increased 4-hydroxy-6-methyl-2-pyrone. Molecular studies identified a total of 12 novel mutations, including a large deletion of HMGCS2 exon 1 in two families, highlighting the need to perform quantitative gene analyses. There are now 26 known HMGCS2 mutations, which are reviewed in the text. 4-Hydroxy-6-methyl-2-pyrone and related metabolites are markers for HMCS2 deficiency. Detection of these metabolites will streamline the biochemical diagnosis of this disorder.

Characterization of Verona Integron-Encoded Metallo-ß-Lactamase-Type Carbapenemase-Producing Escherichia coli Isolates Collected over a 16-Year Period in Bolzano (Northern Italy).

Multidrug-resistant Escherichia coli, particularly carbapenemase producers, are a major source of concern. This study aims to investigate the long-term epidemiology of Verona integron-encoded metallo-ß-lactamase (VIM)-producing E. coli in the health district of Bolzano, Northern Italy, by examining the phenotypic and genotypic characteristics of 26 isolates obtained during 2005-2020. Isolates were identified with matrix-assisted laser desorption/ionization time-of-flight, susceptibility testing was by Vitek 2, Sensititre, and Etest; carbapenemase activity was confirmed by Etest and Carbapenemase Inactivation Method (CIM) test; and the VIM-antigen was identified by the NG-Test CARBA 5. Genome sequencing was performed on an Illumina MiSeq platform. Carbapenem minimum inhibitory concentrations varied across methodologies, and overall category agreement between phenotypic methods was low. All 23 sequenced isolates contained blaVIM-1. Eleven (47.8%) isolates belonged to the clonal lineage ST131, with fimH30 being the most common subclone. In Bolzano ST131-fimH30 was present as early as 2005. While the ST131 clonal lineage predominated for the first 10 years, various clonal lineages were present, especially in subsequent years, indicating the concurrent circulation of multiple clonal lineages. Future efforts should focus on the implementation of surveillance methods, including genomic analysis, as well as the use of updated infection control strategies and antibiotic stewardship programs to prevent the spread of these carbapenem-resistant strains.

Genotype-based databases for variants causing rare diseases.

Inherited diseases are the result of DNA sequence changes. In recessive diseases, the clinical phenotype results from the combined functional effects of variants in both copies of the gene. In some diseases there is often considerable variability of clinical presentation or disease severity, which may be predicted by the genotype. Additional effects may be triggered by environmental factors, as well as genetic modifiers which could be nucleotide polymorphisms in related genes, e.g. maternal ApoE or ABCA1 genotypes which may have an influence on the phenotype of SLOS individuals. Here we report the establishment of genotype variation databases for various rare diseases which provide individual clinical phenotypes associated with genotypes and include data about possible genetic modifiers. These databases aim to be an easy public access to information on rare and private variants with clinical data, which will facilitate the interpretation of genetic variants. The created databases include ACAD8 (isobutyryl-CoA dehydrogenase deficiency (IBD)), ACADSB (short-chain acyl-CoA dehydrogenase (SCAD) deficiency), AUH (3-methylglutaconic aciduria (3-MGCA)), DHCR7 (Smith-Lemli-Opitz syndrome), HMGCS2 (3-hydroxy-3-methylglutaryl-CoA synthase 2 deficiency), HSD17B10 (17-beta-hydroxysteroid dehydrogenase X deficiency), FKBP14 (Ehlers-Danlos syndrome with progressive kyphoscoliosis, myopathy, and hearing loss; EDSKMH) and ROGDI (Kohlschütter-Tönz syndrome). These genes have been selected because of our specific research interests in these rare and metabolic diseases. The aim of the database was to include all identified individuals with variants in these specific genes. Identical genotypes are listed multiple times if they were found in several patients, phenotypic descriptions and biochemical data are included as detailed as possible in view also of validating the proposed pathogenicity of these genotypes. For DHCR7 genetic modifier data (maternal APOE and ABCA1 genotypes) is also included. Databases are available at http://databases.lovd.nl/shared/genes and will be updated based on periodic literature reviews and submitted reports.